gas *

[md5332]

I have a Trane gas furnace. The gas monoxide detector had started to beep when heat is first called for but would stop. It now beeps intermittently but not constant. It's reading 3500.
You can smell the gas from the outside but not internally. What might be causing * Thank you anybody that can help.
Md5332

[juster]

Carbon monoxide has no smell, If the detector is going off maybe you have a faulty heat exchanger, or a faulty detector. The cheapest test is to replace the detector. Do this right now. Do not wait. If the new detector still reads the same then then call a mechanic ASAP to check the furnace and shut the furnace off. Do not turn it back on until checked.

[Freon]

Is it registering the presence of natural gas or carbon * If you don't know, buy a CO only detector and use it ASAP so you know exactly what you're looking * Is this a draft induced or gravity supplied combustion *

If there has been no work done on the gas piping, I would doubt that's the cause. Also you can smell it. But you can use very soapy water on each connection point of the gas piping (couplings, unions... all joints) to check for a gas leak. If it's a CO problem and a gravity combustion air flow, I would check the entire exhaust flue for blockage. It is possible, until the flue heats up and the draft establishes itself (gravity system), you may have a little CO spilling into the furnace room. You will want to check the flame to be sure it's blue... not orange. Complete combustion is the best way to avoid CO issues.

Finally, it could be the heat exchanger but rule out everything else first. You may need a pro with the equipment to look at your heat exchanger. Be sure to have him show you any crack, if he finds one.